LeetCode Maximum Product of Three Numbers Given an integer array, find three numbers whose product is maximum and output the maximum product. Example 1:

Input: [1,2,3]
Output: 6

Example 2:

Input: [1,2,3,4]
Output: 24

Note:

1. The length of the given array will be in range [3,10⁴] and all elements are in the range [-1000, 1000].
2. Multiplication of any three numbers in the input won’t exceed the range of 32-bit signed integer.

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给定一个整数数组，选出三个数，使得乘积最大。 整数数组中可能有负数，所以我们先对数组从小到大排序。如果最小值都大于0，说明没有负数，则三数乘积最大就是最大的前3个数的乘积。 如果有负数，且至少有两个负数，则还需要判断一下最小的两个负数乘以最大的正数的乘积，这个数和前一种情况的大小关系。 代码如下： [cpp] class Solution { public: int maximumProduct(vector<int>& nums) { int n = nums.size(); sort(nums.begin(), nums.end()); int ans1 = nums[n – 1] * nums[n – 2] * nums[n – 3], ans2 = 0; if (nums[0] > 0)return ans1; if (nums[0] < 0 && nums[1] < 0)ans2 = nums[0] * nums[1] * nums[n – 1]; return max(ans1, ans2); } }; [/cpp] 本代码提交AC，用时73MS。]]>